Biopsies could be harvested from all animals. However, histological sections could not be obtained from one rabbit of the 8 weeks group; therefore, eight and seven were achieved for the 1-week and 8-week periods, respectively.

After 1 week of healing, at the treated sites, the antrostomy and close-to-windows regions were occupied by a high proportion of residues of autogenous bone (Fig. 3a), included in soft tissue containing fibroblast-like cells and inflammatory cells (Fig. 4a). At the untreated sites, a high amount of xenograft was found (Fig. 3b), surrounded by soft tissues rich in fibroblast-like cells, that appeared to densify around the particles (Fig. 4b). At the histological assessments, minimal amounts of bone were found after 1 week of healing, especially in close contact with the edges of the antrostomy. In the antrostomy (Table 1), the total amount of new bone was 7.7 ± 11.2% in the treated sites, and 6.1 ± 6.4% in the untreated sites (p = 0.889). In the close-to-window region, 0.6 ± 1% of new bone was found in the treated region, while no new bone was present in the untreated region (p = 0.109).

After 8 weeks of healing, five antrostomies in the treated sites, and three in the untreated sites were repaired with corticalized bone (Fig. 5a, b). Most of the antrostomies presented the remaining defects in the outer contour located in the center (Fig. 6a). Two antrostomies of the treated sites and four of the untreated sites appeared not closed with corticalized bone and presented connective tissue interposed between the edges of the antrostomy (Fig. 6b, c). In the antrostomy region (Table 2; Fig. 7), the new bone was 35.5 ± 20.9% in the treated sites and 28.6 ± 24.1% in the untreated sites, being the difference not statistically significant (p = 0.499). In the close-to-window region, the new bone was 25.8 ± 16.1% and 17.6 ± 16.3% in the treated and untreated sites, respectively. The difference was statistically significant (p = 0.018).

After 1 week (Table 1), the xenograft proportions in the antrostomy were 4.0 ± 7.5% in the treated and 43.5 ± 14.1% in the untreated sites (p = 0.012). After 8 weeks of healing (Table 2), the proportions decreased to 3.4 ± 4.9% and 11.8 ± 13.0% (p = 0.091), respectively.